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    <title>Document</title>
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    <script>
        let a = 1;

        // console.log(Number.isFinite(a));
        // console.log(Number.isFinite(Math.PI));
        // console.log(Number.isFinite(Infinity));

        // let num = NaN;
        // console.log(Number.isNaN(num));

        // let num = 123.123;
        // let num = 123;
        // console.log(Number.isInteger(num));

        // 取整 - 转数字
        // let str = '123.123';
        // console.log(Number.parseInt(str));

        


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